I previously refered to minigzip from libz which copies all trailing
data to the output when decompressing. However, gzip, on the other
hand, drop trailing garbage by default. Consider ZIMAGE append
the kernel size with zero padding, we should drop trailing garbage
as well.
Before this change, the root manager package name is only written into
the database after the repackaged APK is installed. In the time between
the repackaged APK being installed and the package name being written
into the database, if some operation calls `get_manager`, the Magisk
daemon will cache this result and ignore the repackaged APK, even if
the package name is set afterwards, because the cache won't be
invalidated. The result is that the repackaged manager APK will not be
recognized as the root manager, breaking the hide manager feature.
This race condition is more likely to happen when Zygisk is enabled,
because `get_manager` is called with a very high frequency in that case.
To fix the issue, we have to set the new package name into the database
BEFORE installing the repackaged APK. We also stop pruning the
database if the repackaged manager is not found, moving this logic into
the Magisk app. By doing so, we can guarantee that the instant after
the repackaged manager APK is installed, the Magisk daemon will
immediately pick it up and treat it as the root manager.
Another small optimization: when the requester is root, simply bypass
the whole database + manager package check. Since the Magisk app hiding
APK installation proces will call `su` several times to run `pm` under
different UIDs, doing this opimization will reduce the amount of
unnecessary database query + filesystem traversals.
